The languages of the Miluk and Hanis people were mutually unintelligible but are both included in the Coos family of the Penutian family of languages.    From Wordnik.com.  [South Slough National Estuarine Research Reserve, Oregon] Reference

Even if Kennewick Man spoke a non-Penutian language, historic Sahaptin-speakers might have inherited their "cultural core" of knowledge, belief, and practice with respect to their environmental relationships from the earlier group to which Kennewick Man belonged.    From Wordnik.com.  [Spirit Cave & Kennewick] Reference

Kennewick Man may have spoken a Proto-Penutian language, but other possibilities cannot be ruled out, in particular, that the group to which Kennewick Man belonged spoke a language that was not Penutian -- a language now extinct or ancestral to languages spoken outside the present region -- and that the Penutian-speaking predecessors of the historic occupants of this region either displaced this earlier group or arrived after that group had moved elsewhere or had died out.    From Wordnik.com.  [Spirit Cave & Kennewick] Reference